
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" name="viewport">
    <title>移动端图片压缩上传demo</title>

    <style>
        *{margin: 0;padding: 0;}
        li{list-style-type: none;}
        a,input{outline: none;-webkit-tap-highlight-color:rgba(0,0,0,0);}
        #choose{display: none;}
        canvas{width: 100%;border: 1px solid #000000;}
        #upload{display: block;margin: 10px;height: 60px;text-align: center;line-height: 60px;border: 1px solid;border-radius: 5px;cursor: pointer;}
        .touch{background-color: #ddd;}
        .img-list{margin: 10px 5px;}
        .img-list li{position: relative;display: inline-block;width: 100px;height: 100px;margin: 5px 5px 20px 5px;border: 1px solid rgb(100,149,198);background: #fff no-repeat center;background-size: cover;}
        .progress{position: absolute;width: 100%;height: 20px;line-height: 20px;bottom: 0;left: 0;background-color:rgba(100,149,198,.5);}
        .progress span{display: block;width: 0;height: 100%;background-color:rgb(100,149,198);text-align: center;color: #FFF;font-size: 13px;}
        .size{position: absolute;width: 100%;height: 15px;line-height: 15px;bottom: -18px;text-align: center;font-size: 13px;color: #666;}
        .tips{display: block;text-align:center;font-size: 13px;margin: 10px;color: #999;}
        .pic-list{margin: 10px;line-height: 18px;font-size: 13px;}
        .pic-list a{display: block;margin: 10px 0;}
        .pic-list a img{vertical-align: middle;max-width: 30px;max-height: 30px;margin: -4px 0 0 10px;}
    </style>
</head>
<body>
<input type="file" id="choose" accept="image/*" multiple>
<ul class="img-list"></ul>
<a id="upload">上传图片</a>
<span class="tips">只允许上传jpg、png及gif</span>
<div class="pic-list">
    你上传的图片(图片有效期为1分钟)：
</div>
<script src="../../b2c/lib/js/jquery/jquery-2.1.4.js"></script>

<script>
    var filechooser = document.getElementById("choose");
    //    用于压缩图片的canvas
    var canvas = document.createElement("canvas");
    var ctx = canvas.getContext('2d');
    //    瓦片canvas
    var tCanvas = document.createElement("canvas");
    var tctx = tCanvas.getContext("2d");
    var maxsize = 100 * 1024;
    $("#upload").on("click", function() {
                filechooser.click();
            })
            .on("touchstart", function() {
                $(this).addClass("touch")
            })
            .on("touchend", function() {
                $(this).removeClass("touch")
            });
    filechooser.onchange = function() {
        if (!this.files.length) return;
        var files = Array.prototype.slice.call(this.files);
        if (files.length > 9) {
            alert("最多同时只可上传9张图片");
            return;
        }
        files.forEach(function(file, i) {
            if (!/\/(?:jpeg|png|gif)/i.test(file.type)) return;
            var reader = new FileReader();
            var li = document.createElement("li");
//          获取图片大小
            var size = file.size / 1024 > 1024 ? (~~(10 * file.size / 1024 / 1024)) / 10 + "MB" : ~~(file.size / 1024) + "KB";
            li.innerHTML = '<div class="progress"><span></span></div><div class="size">' + size + '</div>';
            $(".img-list").append($(li));
            reader.onload = function() {
                var result = this.result;
                var img = new Image();
                img.src = result;
                $(li).css("background-image", "url(" + result + ")");
                //如果图片大小小于100kb，则直接上传
                if (result.length <= maxsize) {
                    img = null;
                    upload(result, file.type, $(li));
                    return;
                }
//      图片加载完毕之后进行压缩，然后上传
                if (img.complete) {
                    callback();
                } else {
                    img.onload = callback;
                }
                function callback() {
                    var data = compress(img);
                    upload(data, file.type, $(li));
                    img = null;
                }
            };
            reader.readAsDataURL(file);
        })
    };
    //    使用canvas对大图片进行压缩
    function compress(img) {
        var initSize = img.src.length;
        var width = img.width;
        var height = img.height;
        //如果图片大于四百万像素，计算压缩比并将大小压至400万以下
        var ratio;
        if ((ratio = width * height / 4000000) > 1) {
            ratio = Math.sqrt(ratio);
            width /= ratio;
            height /= ratio;
        } else {
            ratio = 1;
        }
        canvas.width = width;
        canvas.height = height;
//        铺底色
        ctx.fillStyle = "#fff";
        ctx.fillRect(0, 0, canvas.width, canvas.height);
        //如果图片像素大于100万则使用瓦片绘制
        var count;
        if ((count = width * height / 1000000) > 1) {
            count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片
//            计算每块瓦片的宽和高
            var nw = ~~(width / count);
            var nh = ~~(height / count);
            tCanvas.width = nw;
            tCanvas.height = nh;
            for (var i = 0; i < count; i++) {
                for (var j = 0; j < count; j++) {
                    tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);
                    ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
                }
            }
        } else {
            ctx.drawImage(img, 0, 0, width, height);
        }
        //进行最小压缩
        var ndata = canvas.toDataURL('image/jpeg', 0.1);
        console.log('压缩前：' + initSize);
        console.log('压缩后：' + ndata.length);
        console.log('压缩率：' + ~~(100 * (initSize - ndata.length) / initSize) + "%");
        tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
        return ndata;
    }
    //    图片上传，将base64的图片转成二进制对象，塞进formdata上传
    function upload(basestr, type, $li) {
        var text = window.atob(basestr.split(",")[1]);
        var buffer = new Uint8Array(text.length);
        var pecent = 0, loop = null;
        for (var i = 0; i < text.length; i++) {
            buffer[i] = text.charCodeAt(i);
        }
        var blob = getBlob([buffer], type);
        var xhr = new XMLHttpRequest();
        var formdata = getFormData();
        formdata.append('imagefile', blob);
        xhr.open('post', '/cupload');
        xhr.onreadystatechange = function() {
            if (xhr.readyState == 4 && xhr.status == 200) {
                var jsonData = JSON.parse(xhr.responseText);
                var imagedata = jsonData[0] || {};
                var text = imagedata.path ? '上传成功' : '上传失败';
                console.log(text + '：' + imagedata.path);
                clearInterval(loop);
                //当收到该消息时上传完毕
                $li.find(".progress span").animate({'width': "100%"}, pecent < 95 ? 200 : 0, function() {
                    $(this).html(text);
                });
                if (!imagedata.path) return;
                $(".pic-list").append('<a href="' + imagedata.path + '">' + imagedata.name + '（' + imagedata.size + '）<img src="' + imagedata.path + '" /></a>');
            }
        };
        //数据发送进度，前50%展示该进度
        xhr.upload.addEventListener('progress', function(e) {
            if (loop) return;
            pecent = ~~(100 * e.loaded / e.total) / 2;
            $li.find(".progress span").css('width', pecent + "%");
            if (pecent == 50) {
                mockProgress();
            }
        }, false);
        //数据后50%用模拟进度
        function mockProgress() {
            if (loop) return;
            loop = setInterval(function() {
                pecent++;
                $li.find(".progress span").css('width', pecent + "%");
                if (pecent == 99) {
                    clearInterval(loop);
                }
            }, 100)
        }
        xhr.send(formdata);
    }
    /**
     * 获取blob对象的兼容性写法
     * @param buffer
     * @param format
     * @returns {*}
     */
    function getBlob(buffer, format) {
        try {
            return new Blob(buffer, {type: format});
        } catch (e) {
            var bb = new (window.BlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder);
            buffer.forEach(function(buf) {
                bb.append(buf);
            });
            return bb.getBlob(format);
        }
    }
    /**
     * 获取formdata
     */
    function getFormData() {
        var isNeedShim = ~navigator.userAgent.indexOf('Android')
                && ~navigator.vendor.indexOf('Google')
                && !~navigator.userAgent.indexOf('Chrome')
                && navigator.userAgent.match(/AppleWebKit\/(\d+)/).pop() <= 534;
        return isNeedShim ? new FormDataShim() : new FormData()
    }
    /**
     * formdata 补丁, 给不支持formdata上传blob的android机打补丁
     * @constructor
     */
    function FormDataShim() {
        console.warn('using formdata shim');
        var o = this,
                parts = [],
                boundary = Array(21).join('-') + (+new Date() * (1e16 * Math.random())).toString(36),
                oldSend = XMLHttpRequest.prototype.send;
        this.append = function(name, value, filename) {
            parts.push('--' + boundary + '\r\nContent-Disposition: form-data; name="' + name + '"');
            if (value instanceof Blob) {
                parts.push('; filename="' + (filename || 'blob') + '"\r\nContent-Type: ' + value.type + '\r\n\r\n');
                parts.push(value);
            }
            else {
                parts.push('\r\n\r\n' + value);
            }
            parts.push('\r\n');
        };
        // Override XHR send()
        XMLHttpRequest.prototype.send = function(val) {
            var fr,
                    data,
                    oXHR = this;
            if (val === o) {
                // Append the final boundary string
                parts.push('--' + boundary + '--\r\n');
                // Create the blob
                data = getBlob(parts);
                // Set up and read the blob into an array to be sent
                fr = new FileReader();
                fr.onload = function() {
                    oldSend.call(oXHR, fr.result);
                };
                fr.onerror = function(err) {
                    throw err;
                };
                fr.readAsArrayBuffer(data);
                // Set the multipart content type and boudary
                this.setRequestHeader('Content-Type', 'multipart/form-data; boundary=' + boundary);
                XMLHttpRequest.prototype.send = oldSend;
            }
            else {
                oldSend.call(this, val);
            }
        };
    }
</script>
</body>
</html>
